On part of the equipment in the quarry you see "Jansen" written on the face of it. That is yet another nod to the director of the episode, Jansen Yee.
There are street signs you see when you are introduced to "Black Villains" house in Detroit. It is the intersection corner of Hayes and Phillip streets. Actually, those two streets are 1 block apart in Detroit, and it is spelled "Philip st" for the actual street in Detroit, not Phillip as seen in the episode.